I was at a band practice for the first time with my friends in one of their basements. My amp when on would randomly out of no where make static noises as if their were a loose cable but when I got home and plugged in my amp the sound never came back. I wanna know if it’s a voltage thing like maybe the outlet isn’t enough because they all had smaller amps and mine was a medium size marshall valvestate 40v.

  • 2
    It's not 'a voltage thing'. It's probably 'a grounding or RF interference thing' but we don't have nearly enough information to work with.
    – Tetsujin
    Nov 6 '20 at 18:39
  • What do you mean a ground or RF interference what is that
    – Leighton
    Nov 6 '20 at 22:52
  • 3
    Grounding issues can happen if either the amp or socket has no Earth connection, or if two pieces of equipment are on different ring mains. RF [radio frequency] interference can be from any other electrical item in the vicinity - microwave, washing machine, air-con etc etc. These are both much easier to figure out if you're there than in text ;)
    – Tetsujin
    Nov 7 '20 at 9:16
  • 3
    @Leighton - we have a number of posts here on RF interference. Worth a read through them.
    – Doktor Mayhem
    Nov 7 '20 at 13:30
  • @tetsujin what are ring mains
    – Leighton
    Nov 10 '20 at 0:44

Dude, your getting interference from something there. You may need a power conditioner ran on your amp, it a device that takes an AC input and removes all the noise and hum out of the power circuit, giving a smooth AC sine wave with no noise. Now if its radio interference, your stuck with it, they try and design circuits in an amp to not give any interference, but will take all interference. Half of the junk in an amp is designed for noise reduction and to protect it from interference, they design specific circuits to protect the amp from foreign signals. I would tell you to take your amp apart and line the cavity, where the electronics are, with aluminum foil, or any other sheet metal to protect it more from radio interference. I had a Marshall 80 watt, solid state amp that would pick up radio from Mexico, well something Spanish. We used to laugh between songs cause my amp had this radio station on it, while we were silent. Radio interference is a tough one to beat, but it just depends on where it's coming from, the AC power source or if it's radio waves. Don't no more than what I'm telling you except your problem may not be helped. Good luck!!!


Too many possibilities with that description.

Cell phone interference Dodgy cable microphonic valve mismatched earths poorly shielded pickups dry joint in the guitar radio - remember your lead acts like an aerial and so on, and all the combinations

A 40W amp draws half the current of a light bulb - it's not going to be a lack of supply - maybe if you had a 1000W bass amp, but even then it's unlikely.


This sounds typical of cellphone interference. Was yours perchance on top of your amp during the practice session?

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